DE1950676A1 - Pitting inhibitors for internal combustion - engines - Google Patents

Abstract

Mechanical corrosion inhibitors composed of 0.05% aqueous solutions containing 0.1% sodium chloride and a gel-containing polymer. Claimed polymers are, Poly(meth)acrylic acid. Polymers of a vinyl ether, isobutylene or ethylene with maleic acid or styrene with mallic acid. The claimed coolants contain a chemical corrosion inhibitor and or an antifreeze. The corrosion inhibitor comprises a mixture of sodium nitrate, sodium mercapto benzothiazole, N-dihydroxyethyl-cyclohexylamine and N-dihydroxyethyl cyclohexylamine benzoate. These liquids are used for internal combustion engine esp. fast-running diesel engines.

Description

Cavitation inhibitors Cavitation is mechanical Corrosion of a pipe system caused by a liquid flowing through this system. Cavitation occurs particularly strongly in closed pipe systems made of metals, which are traversed by aqueous liquids, especially when it comes to deals with fast flowing liquids. Such systems are e.g. cooling circuits of internal combustion engines such as

fast running diesel engines.

Cavitation mainly manifests itself in the form of pitting or pitting on the metal lines.

Attempts have already been made to prevent cavitation in circuits of this type by adding to the circulating aqueous liquids. For this purpose, the circulating fluid has been emulsified with oil or the fluid has been or polyhydric alcohols with 6-20 carbon atoms or polyalkylene glycols with Molecular weights of 300 - 15,000 added.

Mixtures of these substances have also been used.

Also water-soluble polymers e.g. polyvinylpyrrolidone (molecular weight 750,000) and polyvinyl alcohol (molecular weight 55,000) have already been proposed for this purpose been; The effectiveness of these substances is not satisfactory; also are the most of these substances in water too little or only at higher ones Temperatures soluble, the effectiveness of an emulsion is very often due to segregation nullified.

It has now been found that gel-containing water-soluble polymers that in 0.05 percent aqueous solution in the presence of 0.1% sodium chloride at 250 C has a viscosity number @@@ # = 1 = 10, a gel content of 5 - 30% and a degree of swelling of 10 - 1 000% (determined by centrifugation at 50 000 g) are highly effective Are cavitation inhibitors.

The invention thus relates to the use of these gel-containing water-soluble polymers as cavitation inhibitors in aqueous liquids. In general, amounts between 0.01 and 0.5% by weight, preferably 0.01-0.1 % By weight, based on the aqueous liquid.

Examples of polymers are salts of polycrylic acids, polymethacrylic acids, of copolymers of vinyl ethers, isobutylene or ethylene and maleic acid or Styrene and maleic acid into consideration. The gel fractions can by copolymerization be adjusted with di- or polyfunctional monomers.

Divinylbenzene, trivinylbenzene, glycol dimethacrylate, Methylenebisacrylamide can be used.

Chemical corrosion of the usually occurs along with cavitation Systems, i.e. a chemical attack by the circulating fluid on the Piping system. A number of inhibitors are known to protect against chemical corrosion, e.g. benzoates, nitrites, phosphates, borates, silicates and especially for the protection of Non-ferrous metals benthiazole; Triazoles (e.g. benzotriazole) and oxyquinoline. It is possible and is generally preferred, the cavitation inhibitors of the invention to be used in conjunction with corrosion inhibitors of this type. The specially applied Mixture is usually matched to the material of the pipe system. The mixture can then also have more Additives such as buffer substances or alkalizing agents (to regulate the pH value) or anti-foaming agents.

In the special case of the cooling liquids, the usual Antifreeze agents, for example higher or polyhydric alcohols, preferably ethylene glycol be added.

The inhibitory effect against cavitation was based on model tests determined. For this purpose, the test arrangement by A.

Crawford, as described in "Ultrasonics" July / September 1964, Pages 120-123 is described. In these experiments a 5 µ thick platinum foil, which is in the liquid to be examined, treated with ultrasound, until the first pitting (with an initial size of maximum 1 mm in diameter) shows. The applied ultrasound device works at a frequency of 21.8 kHz and has an output of 100 watts. The measure for the cavitation inhibition is used the "sound work" in watt-seconds, (i.e. the product of sound power and exposure time) which must be applied until the first pitting occurs.

The following table 1 gives the cavitation inhibition for a series of aqueous liquids. Experiments 1-6 do not contain any according to the invention Cavitation inhibitors.

Experiments 7 and 8 each contain 0.1 percent by weight of one according to the invention Cavitation inhibitor. When comparing them, one can see that in these two last Trying to do much higher sound work is required to trigger the cavitation.

Table 1 Cavitation inhibition serial no. Composition of the test liquids in Watt seconds 1distilled water 1200 2 drinking water 20 ° dGH 2535 3 drinking water 20 ° dGH 75 tle. # 16200 Glycol 25 tle. 4 distilled water Sodium nitrite 0.2 wt. Mercaptobenzothiazole Sodium 0.04 "7050 N-dihydroxyethyl cyclo- hexylamine N-dihydroxyethyl cyclo- hexylamine benzoate 0.1 5 drinking water 200 dGH Sodium nitrite 0.2% by weight Mercaptobenzothiazole Sodium 0.04 "7200 N-dihydroxyethyl cyclo- hexylamine 0.25 N-di-hydroxyethyl-cyclo- hexylamine benzoate 0.1 6 drinking water 20 ° dGH 75 tle. Glycol 25 Tlc. Sodium nitrite 0.2% by weight Mercaptobenzothiazole- # 16200 0.04 " sodium N-di-hydroxyethyl 0.25 cyclohexylamine 0.25 N-di-hydroxyethyl 0.1 " cyclohexylamine benzoate 7 drinking water 20 ° dGH Sodium nitrite 0.2% by weight Mercaptobenzothiazole Sodium 0.04 N-di-hydroxyethyl 0.25 " cyclohexylamine 45300 N-di-hydroxyethyl 0.10 " cyclohexylamine benzoate Continuation: Table 1 Cavitation inhibition serial no. Composition of the test liquids in watt seconds 7 Na salt copolymer X) Styrene, 50 mol% 0.1 wt% Maleic acid 50 mol- Methylenebisacrylamide 0.5 mol% 8 drinking water 75 teaspoons Glycol 25 Na salt copolymer the end 50 mol% styrene? 50 mol% maleic acid 0.1% by weight | 41700 G, 5 mole percent methylenebisacrylamide In the following table 2, according to experiments 9-11, known cooling liquids are compared with a cooling liquid (experiment 12) which contains a cavitation inhibitor according to the invention.

Table 2 Cavitation inhibition (Watt-sec) No. Composition of the test liquid 9 drinking water 75 teaspoons Glycol 25 tle. Borax 0.33% by weight Sodium nitrate 0.10 wt% x) (#) # = 1: 13.0 Gel = 29%, degree of swelling 132% Continuation: Table 2 No. Composition of the test liquid Cavitation inhibition (Watt-sec) 9 sodium nitrite 0.117% by weight Sodium Benzoate 0.75 " Sodium silicate 0.01 " Benztrialzene 0.023 "11800 10 as No. 9 and additionally 2.5% polyethylene oxide, MW 12000 @ 18600 11 as No. 9 and add @@@ n 1.0% polyvinylpyrrolidone, MW 750,000 @ 20600 12 As No. 9 and additionally 0.1% by weight of copolymer 50 mole percent styrene, 50 mole percent maleic acid 0.5 mol% methylenebisacrylamide # (#) # = 1 = 13 55 200

Claims (4)

Claims 1. Use of gel-containing water-soluble polymers, those in 0.05 percent aqueous solution, in the presence of 0.1% sodium chloride, at 25 ° C a viscosity number (#) # = 1 # 10 a gel content of 5 - 50% and a They have a degree of swelling of 10 - 1000% as cavitation inhibitors. 2. Use of polyacrylic acids, polymethacrylic acids, polymers from vinyl ethers, isobutylene or ethylene and maleic acid or styrene and maleic acid as cavitation inhibitors. 3. Aqueous coolant containing 0.01-0.5% of a gel-containing water-soluble polymers, in 0.05 percent aqueous solution, in the presence of 0.1% sodium chloride, at 25 ° C a viscosity number (#) # = 1 # 10, a gel content of 5 - 50% with a degree of swelling of 10 - 1000% has as a cavitation inhibitor and optionally known corrosion inhibitors and / or antifreeze agents. 4. Aqueous cooling liquid according to claim 3 containing as a corrosion inhibitor a mixture of sodium nitrite, mercaptobenzothiazole sodium, N-dihydroxyethyl-cyclohexylamine and N-dihydroxyethyl cyclohexylamine benzoate.